This invention relates to gaseous discharge display and/or memory devices and more particularly to large size high resolution devices of this type embodying a method of spacing the plates with spacer elements that does not inhibit flow of gas particles within the panel, which are substantially invisible and which can be interspersed across the display surface at predetermined or random intervals in accordance with the size of the panel and the specific geometric design of the conductor arrays.
Various methods have been employed in the prior art for maintaining a uniform space or gap between opposing walls of a gas discharge device, primarily involving the use of glass spacers generally in rod form, and various methods of gas panel assembly using such spacers have been proposed. In one arrangement, disclosed in U.S. Pat. No. 3,808,497 to Greeson, Jr. et al, hard glass spacer rods and soft glass sealing rods are spaced about the periphery of a panel during the sealing cycle whereby the space between the plate is controlled by the peripheral glass spacer rods when the glass sealant reflows. In other arrangements for utilizing glass rods in a gas panel fabrication, grooves can be cut in the panel subassembly by scoring the dielectric after reflow to position and retain the glass spacer rods in position during the fabrication of the panel. However, it is essential that the rods maintain their position during assembly with utmost precision so as to avoid intrusion into the operative portions of the display area. This presents a difficult problem in fabrication since the rods are of such dimensions as to make handling extremely difficult and further tend to move readily even from their grooved position during the fabrication process so that additional care must be exercised in the fabrication to prevent lateral movement of the rods.
While this method has been employed successfully albeit with the problems enumerated above, the method of framing the display area with rod glass spacers is limited to panels where the plates are relatively small. As the display area and hence the plate size are increased, spacer means must be introduced at intermediate locations within the chamber to maintain the critical precise spacing between the plates. In methods employed for medial spacing in the prior art, glass spacer rods are positioned between adjacent rows or columns of cells rather than obstruct the display area, thus tending to limit the resolution of the panel. Additionally, glass spacer elements having medial locations in the panel tend to be visible and are considered undesirable from an aesthetic standpoint. Finally, the problem of positioning and maintaining the spacer rods in position at the medial location within the panel during fabrication remains. The length of the sealing rods must be limited since they may tend to impede the flow of gas particles and metastables between adjacent areas separated by such spacer rods. Thus there is need for a spacer technology which will provide uniform spacing between glass plates, particularly in gaseous discharge devices having large display areas of high resolution. It would also be desirable to minimize the size of the spacer elements and at the same time provide greater latitude in their location for aesthetic reasons so so they will not be visible and mar the display area.